Coreless rotating electrical machine for being operated under load exceeding rating, driving method thereof, and driving system including thereof

Abstract

A coreless rotating electrical machine for being operated under load exceeding rated load, driving method thereof, driving system including thereof; coreless rotating electrical machine for being operated under load exceeding rated load, driving method thereof, driving system including thereof, in which air space including air gap is formed by stator consisting of lid-type mount which fixes end face of energizable coreless cylindrical coil and rotor consisting of cylindrical mount or cup-type mount opposingly and rotatably positioned to lid-type mount with plurality of magnets equipped on inner surface of cylindrical or cup-type mount, wherein when load exceeds the rating, operation is enabled by adjusting supply amount of refrigerant liquid so the temperature of cylindrical coil does not exceed allowable maximum temperature at rated operation; refrigerant liquid supplied to air space including air gap to allow cylindrical coil to vaporize refrigerant liquid to cool by latent heat of vaporization of refrigerant liquid.

Claims

1. A coreless rotating electrical machine to be operated continuously under a load exceeding a rating defined for a condition without cooling, comprising: a stator including an energizable coreless cylindrical coil; a lid-type mount which fixes an end face of the cylindrical coil; and a rotor including a cup-type mount opposingly and rotatably positioned with respect to the lid-type mount, wherein: an air gap is formed between the lid-type mount and the cup-type mount, the cup-type mount is equipped with a plurality of magnets, wherein: an outer surface of each of the magnets is faced to an inner surface of the cylindrical coil within the air gap, an inner surface of each of the magnets is faced to an outer surface of the cylindrical coil within the air gap, or an outer surface of each magnet of a first group of the magnets is faced to an inner surface of the cylindrical coil within the air gap and an inner surface of each magnet of a second group of the magnets is faced to an outer surface of the cylindrical coil within the air gap, the lid-type mount is equipped with a channel for supplying a refrigerant liquid to the air gap, and a controlling part which controls supply of the refrigerant liquid and a driving part which drives the rotor are equipped therewith, wherein, when the driving part is activated and the coreless rotating electrical machine is operated continuously under the load exceeding the rating defined for the condition without cooling, the controlling part is activated to adjust the supply of the refrigerant liquid by repeating a first operation of supplying the refrigerant liquid into the air gap to prevent a temperature of the cylindrical coil exceeding an allowable maximum temperature for a continuous operation, allowing the cylindrical coil, which generates heat, to vaporize the refrigerant liquid to cool itself by latent heat of vaporization of the refrigerant liquid, and a second operation to stop the supplying of the refrigerant liquid to heat the cylindrical coil to prevent the temperature of the cylindrical coil falling below a minimum temperature where the refrigerant liquid vaporizes, so as to maintain the temperature of the cylindrical coil in a range between the allowable maximum temperature and the minimum temperature, which enables the coreless rotating electrical machine to be operated continuously under the load exceeding the rating defined for a condition without cooling.

2. The coreless rotating electrical machine as defined in claim 1, wherein the refrigerant liquid is water, and the minimum temperature is 100° C. and the allowable maximum temperature is 125° C.

3. The coreless rotating electrical machine as defined in claim 1, wherein the controlling part comprises a coil temperature detecting sensor for detecting the temperature of the cylindrical coil, a pump for supplying the refrigerant liquid into the air gap, and a controller for adjusting the supply of the refrigerant liquid with on/off commands to the pump in coordination with the coil temperature detecting sensor.

4. The coreless rotating electrical machine as defined in claim 3, further equipped with a refrigerant liquid container which is in communication with the channel.

5. The coreless rotating electrical machine as defined in claim 4, wherein the lid-type mount is further equipped with a circulating means which communicates between the refrigerant liquid container and the air gap.

6. The coreless rotating electrical machine as defined in claim 5, wherein the controlling part collects the refrigerant liquid in a gas phase into the refrigerant liquid container in a liquid phase thereof by the circulating means.

7. The coreless rotating electrical machine as defined in claim 1, further equipped with a refrigerant liquid container which is in communication with the channel, wherein the controlling part comprises a coil temperature detecting sensor for detecting the temperature of the cylindrical coil, an electromagnetic valve for supplying the refrigerant liquid from the refrigerant liquid container arranged at a position higher than the cylindrical coil into the air gap, and a controller for adjusting the supply of the refrigerant liquid with open/close commands to the electromagnetic valve in coordination with the coil temperature detecting sensor.

8. The coreless rotating electrical machine as defined in claim 7, wherein the lid-type mount is further equipped with a circulating means which communicates between the refrigerant liquid container and the air gap.

9. The coreless rotating electrical machine as defined in claim 8, wherein the controlling part collects the refrigerant liquid in a gas phase into the refrigerant liquid container in a liquid phase thereof by the circulating means.

10. The coreless rotating electrical machine as defined in claim 1, wherein the rotor further includes a drive shaft fixed to a center part of the cup-type mount and rotatably coupled to a center part of the lid-type mount.

11. The coreless rotating electrical machine as defined in claim 1, wherein the cylindrical coil is formed from a laminate of electrically conductive metal sheets having linear parts being spaced in an axial direction covered with insulating layers formed to a cylindrical form.

12. The coreless rotating electrical machine as defined in claim 1, wherein the cylindrical coil is formed from a linear conductor covered with an insulating layer formed to a cylindrical form.

13. A driving method of a coreless rotating electrical machine for being operated continuously under a load exceeding a rating defined for a condition without cooling, the coreless rotating electrical machine comprising a stator including an energizable coreless cylindrical coil, a lid-type mount which fixes an end face of the cylindrical coil, and a rotor including a cup-type mount opposingly and rotatably positioned with respect to the lid-type mount, wherein: an air gap is formed between the lid-type mount and the cup-type mount, the cup-type mount is equipped with a plurality of magnets, wherein: an outer surface of each of the magnets is faced to an inner surface of the cylindrical coil within the air gap, an inner surface of each of the magnets is faced to an outer surface of the cylindrical coil within the air gap, or an outer surface of each magnet of a first group of the magnets is faced to an inner surface of the cylindrical coil within the air gap and an inner surface of each magnet of a second group of the magnets is faced to an outer surface of the cylindrical coil within the air gap, the lid-type mount is equipped with a channel for supplying a refrigerant liquid to the air gap, and a controlling part which controls supply of the refrigerant liquid and a driving part which drives the rotor are equipped therewith, wherein the driving method includes: a step of activating the driving part and operating the coreless rotating electrical machine continuously under the load exceeding the rating defined for a condition without cooling; and a step of activating the controlling part to adjust the supply of the refrigerant liquid by repeating a first operation of supplying the refrigerant liquid into the air gap to prevent a temperature of the cylindrical coil exceeding an allowable maximum temperature for a continuous operation, allowing the cylindrical coil, which generates heat, to vaporize the refrigerant liquid to cool itself by latent heat of vaporization of the refrigerant liquid, and a second operation to stop the supplying of the refrigerant liquid to heat the cylindrical coil to prevent the temperature of the cylindrical coil falling below a minimum temperature where the refrigerant liquid vaporizes, so as to maintain the temperature of the cylindrical coil in a range between the allowable maximum temperature and the minimum temperature, which enables the coreless rotating electrical machine to be operated continuously under the load exceeding the rating defined for a condition without cooling.

14. The driving method as defined in claim 13, wherein the refrigerant liquid is water, and the minimum temperature is 100° C. and the allowable maximum temperature is 125° C.

15. The driving method as defined in claim 13, wherein the controlling part comprises a coil temperature detecting sensor, a pump for supplying the refrigerant liquid into the air gap, and a controller for adjusting the supply of the refrigerant liquid with on/off commands to the pump, the driving method further includes a step of activating the coil temperature detecting sensor to detect the temperature of the cylindrical coil, and adjusting the supply of the refrigerant liquid so as to maintain the temperature of the cylindrical coil in a range between the allowable maximum temperature and the minimum temperature includes that the controller commands the pump to be on/off based on a detected temperature of the cylindrical coil.

16. The driving method as defined in claim 15, wherein the coreless rotating electrical machine is further equipped with a refrigerant liquid container which is in communication with the channel.

17. The driving method as defined in claim 16, wherein the lid-type mount is further equipped with a circulating means which communicates between the refrigerant liquid container and the air gap.

18. The driving method as defined in claim 17, further including a step of the controlling part activating the circulating means to collect the refrigerant liquid in a gas phase into the refrigerant liquid container in a liquid phase thereof.

19. The driving method as defined in claim 13, wherein the coreless rotating electrical machine is further equipped with a refrigerant liquid container which is in communication with the channel, the controlling part comprises a coil temperature detecting sensor for detecting the temperature of the cylindrical coil, an electromagnetic valve for supplying the refrigerant liquid from the refrigerant liquid container arranged at a position higher than the cylindrical coil into the air gap, and a controller for adjusting the supply of the refrigerant liquid with open/close commands to the electromagnetic valve in coordination with the coil temperature detecting sensor, the driving method further comprises a step of activating the coil temperature detecting sensor to detect a temperature of the cylindrical coil, and adjusting the supply of the refrigerant liquid so as to maintain the temperature of the cylindrical coil in a range between the allowable maximum temperature and the minimum temperature includes that the controller operates the electromagnetic valve based on a detected temperature of the cylindrical coil.

20. The driving method as defined in claim 19, wherein the lid-type mount is further equipped with a circulating means which communicates between the refrigerant liquid container and the air gap.

21. The driving method as defined in claim 20, further including a step of the controlling part activating the circulating means to collect the refrigerant liquid in a gas phase into the refrigerant liquid container in a liquid phase thereof.

22. The driving method as defined in claim 13, wherein the rotor further includes a drive shaft fixed to a center part of the cup-type mount and rotatably coupled to a center part of the lid-type mount.

23. The driving method as defined in claim 13, wherein the cylindrical coil is formed from a laminate of electrically conductive metal sheets having linear parts being spaced in a longitudinal direction covered with insulating layers formed to a cylindrical form.

24. The driving method as defined in claim 13, wherein the cylindrical coil is formed from a linear conductor covered with an insulating layer formed to a cylindrical form.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a cross sectional schematic diagram of a coreless rotating electrical machine comprising a rotor consisting of a cylindrical mount opposingly and rotatably positioned with respect to a stator consisting of a lid-type mount including a cylindrical coil, which is an embodiment of the present invention.

(2) FIG. 2 is a perspective diagram of a partially cutout cureless rotating electrical machine shown in FIG. 1.

(3) FIG. 3 is a cross sectional schematic diagram of a coreless rotating electrical machine comprising a rotor consisting of a cup-type mount opposingly and rotatably positioned with respect to a stator consisting of a lid-type mount including a cylindrical coil, which is another embodiment of the present invention.

(4) FIG. 4 is a perspective diagram of a partially cutout coreless rotating electrical machine shown in FIG. 3.

(5) FIG. 5 is a schematic diagram representing the coreless rotating electrical machine, a driving method thereof, and a driving system including thereof, comprising a controlling part or controlling device, for controlling flow volume of a refrigerant liquid by a pump, equipped in relation to the stator, and a driving part or driving device equipped in relation to the rotor, of the cureless rotating electrical machine shown in FIG. 1 or 3.

(6) FIG. 6 is a schematic diagram representing the cureless rotating electrical machine, a driving method thereof, and a driving system including thereof, comprising a controlling part or controlling device, for controlling flow volume of a refrigerant liquid by an electromagnetic valve, equipped in relation to the stator, and a driving part or driving device equipped in relation to the rotor, of the coreless rotating electrical machine shown in FIG. 1 or 3.

(7) FIG. 7 is a schematic diagram of a driving test of a measured motor (CP50) of the coreless rotating electrical machine comprising a rotor consisting of a cup-type mount opposingly and rotatably positioned with respect to a stator consisting of the lid-type mount including a cylindrical coil.

(8) FIG. 8 is a detailed diagram representing dimensions of the measured motor (CP50) shown in FIG. 7.

(9) FIG. 9 is what has excerpted a shift of load torque and a shift of temperature t of the cylindrical coil with respect to time (seconds) from start-up up to when 720 seconds (12 minutes) has passed in a case where applied voltage of the measured motor (CP50) is set to 24V, and a torque, with which the temperature of the cylindrical coil does not exceed an allowable maximum temperature t.sub.M (=130° C.), even if the measured motor (CP50) is operated without the refrigerant liquid (pure water) supplied to the cylindrical coil, is used as a rated torque of the measured motor (CP50).

(10) FIG. 10 is a control flow of supplying a refrigerant liquid, in which a load of the measured motor (CP50) is raised by a variable load of an electric generator via a torque sensor shown in FIG. 7, the measured motor is operated such that a temperature difference .sub.Δt between the maximum temperature t.sub.c1 of the cylindrical coil under control and the minimum temperature t.sub.c2 of the cylindrical coil under control comes narrow, under a condition where the temperature of the cylindrical coil does not exceed the allowable maximum temperature t.sub.M and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes, and the maximum torque and refrigerant liquid flow volume are measured, in a case where applied voltage of the measured motor (CP50) is set to 24V.

(11) FIG. 11 is a table of current (Arms), rotational speed (rpm), output (W), pump conveyed amount (ml/min), total pump activation time (sec) in 10 minutes and refrigerant (pure water) amount (ml) in 10 minutes when the measured motor (CP50) is driven with respective load torque T (T.sub.1=0.33 Nm, T.sub.2=0.36 Nm, T.sub.3=0.39 Nm, T.sub.4=0.42 Nm) exceeding the rated torque.

(12) FIG. 12 is a graph of the current (Arms) and the refrigerant (pure water) amount (ml) in 10 minutes with respect to the load torque T of FIG. 11.

(13) FIG. 13 represents a shift of temperature t of the cylindrical coil, a shift of on/off timing of the pump and a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump during a period from start-up up to when 180 to 360 seconds has passed from then, in a case of the load torque T=0.33 Nm.

(14) FIG. 14 represents a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump, and a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump during a period from start-up up to when 180 to 360 seconds has passed from then, in a case of the load torque T=0.39 Nm.

(15) FIG. 15 represents a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump, and a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump during a period from start-up up to when 180 to 360 seconds has passed from then, in a case of the load torque T=0.39 Nm.

(16) FIG. 16 represents a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump, and a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump during a period from start-up up to when 180 to 360 seconds has passed from then, in a case of the load torque T=0.42 Nm.

(17) FIG. 17 represents a shift of temperature t of the cylindrical coil, a shift of on/off pulse of the pump, and a shift of temperature t of the coil and a shift of on/off pulse of the pump during a period from start-up up to when 180 to 420 seconds has passed from then, in a case where the load torque is changed as T.sub.1=0.33 Nm (300 seconds), T.sub.4=0.42 Nm (300 seconds) and then T.sub.1=0.33 Nm (120 seconds).

(18) FIG. 18 represents a shift of temperature t, a shift of on/off pulse of the pump, and a shift of temperature t of the coil and a shift of on/off pulse of the pump during a period from start-up up to when 180 to 420 seconds has passed from then, in a case where the measured motor (CP50), of which load torque is changed as shown in FIG. 17, is set such that a supply start temperature t.sub.L1 of refrigerant liquid is 110° C. (the refrigerant liquid is supplied at a temperature t exceeding such temperature), and a supply stop temperature of refrigerant liquid t.sub.L2 is 90° C. (the supply of the refrigerant liquid is stopped at a temperature t which falls below such temperature).

(19) FIG. 19 is a list of melting temperature ° C., boiling temperature ° C., vaporization heat kJ/kg of representative refrigerant liquids.

(20) FIG. 20 represents a shift of temperature t of the cylindrical coil in a driving test using the measure motor (CP50) in which a fluorinated refrigerant is used with load torque T 0.317 Nm, with respect to each of cases where cooling is performed and where cooling is not performed.

(21) FIG. 21 (Reference diagram) is a coreless rotating electric machine having a configuration in which a refrigerant liquid is supplied only to a second air space of the coreless rotating electrical machine.

(22) The inventors of the present invention have confirmed that a continuous operation of a coreless motor (CP50) is possible by completely controlling a temperature of a cylindrical coil, which is an armature coil, with a load exceeding a rated torque T.sub.0=0.28 Nm being continuously applied to the coreless motor (CP50).

(23) A feature of a basic structure of a coreless rotating electrical machine 10 (hereinafter referred as “coreless motor 10”) equipped with a stator 2 comprising a cylindrical coil 100 of the present invention is that, firstly, a cylindrical coil 100 is used as an armature coil which one end is fixed to a stator 2, wherein the cylindrical coil 100 is made with a laminate of electrically conductive metal sheets having linear parts being spaced in a longitudinal direction covered with insulating layers, or a linear conductor covered with an insulating layer, formed to a cylindrical form. It is an energizable cureless cylindrical coil, preferably having a certain rigidity with a thickness, consisting of two layers or four layers, of 5 mm or less.

(24) A second feature of the basic structure is that, it is a coreless motor 10 having a structure in which one of end faces of the cylindrical coil 100 is closed by an inner surface of a lid-type mount 200 included in the stator 2, and the other end face of the cylindrical coil 100, which is open, is inserted as suspended in an air space or a first air space 40 including an air gap in which a magnetic field is formed by a bottom of a cylindrical mount 300 or a cup-type mount 400 of the rotor 3 consisting of a magnetic body and an inner surface of the cylindrical mount 300 or an outer yoke 430 of the cup-type mount 400 equipped with a plurality of magnets (permanent magnets) 4.

(25) Then, by feeding a refrigerant liquid 80 to an inner face of the cylindrical coil 100, or inside of an inner yoke 420 of the rotor 3 consisting of the cup-type mount 400, the refrigerant liquid 80 is vaporized at the inner face of the cylindrical coil 100, which generates heat, when it passes through the air gap in which the magnetic field is formed. The cylindrical coil 100 is thereby cooled at the inner face with latent heat of vaporization, and entire cylindrical coil including an outer face is instantaneously cooled by heat transfer. This is one of the features of a cooling structure of the coreless motor of the present invention.

(26) A third feature of the basic structure is that a controlling part or controlling device 20, which is activated when the coreless motor 10 is operated under a load exceeding a rating, is arranged in association with the stator 2, and that it comprises a coil temperature detecting sensor 21 for detecting temperature increase of the cylindrical coil 100 in operation. This feature is to have the controlling part or controlling device 20 adjust supply amount of the refrigerant liquid 80 so that the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M under rated operation, in coordination with the coil temperature detecting sensor 21. The coreless motor 10 which continuously operates under the load exceeding the rating is achieved thereby. Driving tests considering various overload conditions are performed for the coreless motor 10 of the present invention as shown in FIGS. 13 to 18 and FIG. 20.

(27) FIG. 7 is a schematic diagram of a driving test apparatus of a measured motor (CP50) based on one embodiment of the coreless rotating electrical machine 10 equipped with the rotor 3 consisting of the cup-type mount 400 opposingly and rotatably positioned with respect to the stator 2 consisting of the lid-type mount 200 including the cylindrical coil 100. FIG. 8 is a detailed diagram of an actually measured structure of the measured motor (CP50).

(28) As apparent from FIG. 7, an output axis 1000, which diameter Φ is 6 mm, of the coreless motor 10 which is the measured motor (CP50) is coupled to an electric generator 32 (m-link CPH80-E) via a torque sensor 34 (UNIPULSE UTM II-5 Nm) to which a torque meter 35 (UNIPULSE TM301) is connected. The electric power generated by the electric generator 32 is made to be consumed by a variable load 33 (in-link VL300), and an arbitrary load is applied to the coreless motor 10 to drive thereof. Current of the coreless motor 10 is measured with a power meter 31 (HIOKI PW3336) which is arranged between a driving part or driving device 30 (a three-phase PWM type, in-link MLD750-ST) and the coreless motor 10. Current I(A), Voltage V(V) and Electric power Pi(W) can be measured by the power meter 31.

(29) Then, temperature t and voltage is input to the controlling part or controlling device 20 (m-link TH300) including a CPU via a device (GRAPHTEC GL-100) which records the temperature t and voltage measured by the coil temperature detecting sensor 21 arranged on the cylindrical coil 100. The controlling part or controlling device 20 activates a refrigerant liquid supply pump 22 (NITTO UPS-112) at an appropriately set temperature t, deactivates the pump, and the refrigerant liquid 80 is supplied to the first air space 40 of the coreless motor 10 from a refrigerant liquid container 81. Flow volume of the refrigerant liquid 80 is made to be adjusted by varying driving voltage of the refrigerant liquid supply pump 22 using a refrigerant liquid flow volume varying device 26 (TOKYO-RIKOSHA TYPE RSA-5) equipped in association with the controlling part or controlling device 20. The coreless motor 10 is further provided with a channel 8 including a pipe 82 and a plurality of slits 423 in the inner yoke 420 of the rotor 3 in an axial direction.

(30) Dimensions of the coreless motor 10 which is the measured motor shown in FIG. 8 are overviewed. An axial length of the output axis coupled and fixed to the stator 2 and rotatably coupled to the rotor 3 is L=81.7 mm. A side of a rectangular bottom of the stator 2 is x=50 mm, an outer diameter of the outer yoke of the rotor 3 is Φ=46.3 mm, an inner diameter is Φ=40 mm, and a thickness is Δ=3.15 mm. A diameter of a rotor axis part is Φ=22.5 mm, which corresponds to an inner diameter Φ of the inner yoke 420. An outer diameter thereof is Φ=27.5 mm, and a thickness is Δ=2.5 mm. A thickness of each of the four magnets 4 equipped on the inner face of the outer yoke 430 is Δ=3.5 mm. A width of the air gap formed by the inner yoke 420 and the outer yoke 430 is Ψ=2.75 mm, and a width of the cylindrical coil 100 equipped as suspended in the air gap is Δ=1.50 mm.

(31) The driving test using the coreless motor 10 which is the measured motor (CP50) is to verify a function effect obtained by directly spraying pure water 80, which is the refrigerant liquid, to the cylindrical coil 100, which generates heat, for cooling thereof by latent heat of vaporization of the pure water 80, and that the continuous operation of the coreless motor 10 is possible even under the load condition exceeding the rating by such cooling function.

(32) A test procedure of the coreless motor 10 is as follows. Voltage V.sub.0=24(V) is set as applied voltage to the driving part or driving device 30 (three-phase PWM type, m-link MLD750-ST) (hereinafter referred as “driving device 30”) shown in FIG. 7. It is also possible to perform the test by setting the voltage V.sub.0 as 36(V) and/or 48(V), higher than 24(V), with the same work, and needless to say, results may be of course different in each of the cases.

(33) Next, a load torque T applied to the coreless motor 10 is raised with the variable load 33 of the electric generator 32. The flow volume of the refrigerant liquid (pure water) 80 is adjusted so as to be corresponded with the setting of load torque T by varying the driving voltage of the refrigerant liquid supply pump 22 using the refrigerant liquid flow volume varying device 26 equipped in association with the controlling part or controlling device 20 (hereinafter referred as “controlling device 20”). The allowable maximum temperature of the cylindrical coil 100 used in the coreless motor 10 is 130° C. Therefore, the adjustment is performed by operating the coreless motor such that the temperature difference .sub.Δt between the maximum temperature t.sub.c1 of the cylindrical coil under control and the minimum temperature t.sub.c2 of the cylindrical coil under control comes narrow, under a condition where the temperature of the cylindrical coil does not exceed the allowable maximum temperature t.sub.M=130° C., and does not fall below the minimum temperature t.sub.N, where the refrigerant liquid (pure water) vaporizes to measure the load torque T and the flow volume of the refrigerant liquid (pure water) 80 at such point.

(34) FIG. 10 is a control flow in which the load of the measured motor (CP50) 10 is raised with the variable load 33 of the electric generator 32 via the torque sensor 34 shown in FIG. 7 to have the coreless motor 10 operated such that the temperature difference .sub.Δt between the maximum temperature t.sub.c1 of the cylindrical coil under control and the minimum temperature t.sub.c2 of the cylindrical coil under control comes narrow, under a condition where the temperature of the cylindrical coil does not exceed the allowable maximum temperature t.sub.M=130° C. and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes.

(35) As apparent from FIG. 10, the coil temperature detecting sensor 21 is read (first read-in), and when the temperature t of the cylindrical coil 100 exceeds t.sub.L1=123° C., the refrigerant liquid supply pump 22 is operated to supply the refrigerant liquid. The coil temperature detecting sensor 21 is read (second read-in) further, and when the temperature t of the cylindrical coil 100 falls below t.sub.L2=122° C., the refrigerant liquid supply pump 22 is deactivated to stop supply of the refrigerant liquid. During such period, in a case where the temperature t of the cylindrical coil does not reach such set temperatures, the first read-in and the second read-in of the coil temperature detecting sensor 21 are repeated.

(36) The maximum torque T.sub.M, when the applied voltage to the driving device 30 of the coreless motor 10 is set to 24V, is thus measured, and the flow volume L.sub.M per minute of the refrigerant liquid (pure water) 80 at such point measured. Operating conditions of the refrigerant liquid supply pump 22 are as in the followings.

(37) (1) Cooling start temperature t.sub.L1=123° C. (the first read-in)

(38) (2) Cooling stop temperature t.sub.L2=122° C. (the second read-in)

(39) When the refrigerant liquid supply pump 22 is switched with respective read-in conditions of (1) and (2) to activate the coreless motor 10, values are: the torque T.sub.M=0.42 Nm and the flow volume L.sub.M=1.141 ml/min.

(40) A technical basis for using the maximum torque T.sub.M and the maximum flow volume L.sub.M is as follows: when the coreless motor is operated with a torque T exceeding 0.42 Nm, the flow volume of the refrigerant liquid 80 also increases. However, we have confirmed that, with the increase of the refrigerant liquid 80, the refrigerant liquid 80 is discharged in a form of a mist (liquid phase) to outside of the coreless motor 10 without being vaporized by the cylindrical coil 100. Therefore, the torque T=0.42 Nm becomes a critical torque which allows the coreless motor 10 to be operated continuously under a load exceeding the rated torque T.sub.0=0.28 Nm.

(41) FIG. 9 represents a torque which allows the coreless motor to be continuously operated without supplying the pure water 80, which is the refrigerant liquid, thereto, and with which the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M=130° C. When the coreless motor 10 is continuously operated under the load torque T.sub.0=0.28 Nm, as apparent form FIG. 9, the temperature of the cylindrical coil 100 reaches 100° C. in 50 seconds, and exceeds 120° C. in 300 seconds (5 minutes). The temperature reaches 127° C. in 720 seconds (12 minutes), and later, temperature equilibration is achieved at the allowable maximum temperature t.sub.M=130° C. or less. FIG. 9 simply represents that the rated torque T.sub.0, which allows the coreless motor to be continuously operated when the refrigerant liquid is not supplied, is T.sub.0=0.28 Nm.

(42) Next, a load torque T exceeding the rated torque T.sub.0 is applied to the coreless motor 10 when the applied voltage to the driving device 30 is set to 24V. Then, as apparent form FIG. 12, the current increases in proportion to the raised load torque T, and with heat generation of the cylindrical coil 100 associated therewith, a supply amount of the refrigerant liquid (pure water) 80 is increased. Thus, it is confirmed that, as a result of an appropriate control of the driving system 1, the continuous operation under the overload condition is possible.

(43) Specifically, the coreless motor 10 is activated in 5 cases in which the load torque T, for continuously operating the coreless motor 10 under the load exceeding the rated torque T.sub.0, is set to T.sub.1=0.33 Nm, T.sub.2=0.36 Nm, T.sub.3=0.39 Nm, T.sub.4=T.sub.M=0.42 Nm, and further, set to T.sub.4=0.42 Nm and lowered to T.sub.1=0.33 Nm and then set to T.sub.4=0.42 Nm again.

(44) It is confirmed that, a normal continuous operation of the coreless motor 10 is possible under any set torque exceeding the rated torque T.sub.0 with a control by the controlling device 20 in which the refrigerant liquid supply pump 22 is switched such that, at the cooling start temperature t.sub.L1=123° C. (the first read-in), the refrigerant liquid is supplied at a temperature t exceeding the cooling start temperature, and at the cooling stop temperature t.sub.L2=122° C. (the second read-in), the supply of the refrigerant liquid is stopped at a temperature t below such temperature, so that the temperature difference .sub.Δt between the maximum temperature t.sub.c1 of the cylindrical coil under control and the minimum temperature t.sub.c2 of the cylindrical coil under control comes narrow, under a condition where the temperature of the cylindrical coil does not exceed the allowable maximum temperature t.sub.M=130° C. thereof and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes.

(45) The operation condition of the refrigerant liquid supply pump 22 is made as: cooling start (first read-in) temperature t.sub.L1=123° C. This is a set value which allows temperature increase due to overshoot at a time when the cooling started, and which the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M=130° C. In addition, the cooling stop (the second read-in) temperature is made as t.sub.L2=122° C. This is a set value which allows temperature decrease due to overshoot at a time when the cooling stopped, and further, which prevents malfunction due to foreign noise etc. for operating the system stably by making hysteresis with the cooling start (first read-in) temperature t.sub.L1=123° C. as 1° C. With such operating conditions, the temperature difference .sub.Δt between the maximum temperature t.sub.c1 of the cylindrical coil under control and the minimum temperature t.sub.c2 of the cylindrical coil under control comes narrow, and thus, stress to the cylindrical coil due to thermal shock is alleviated, and change of electric resistance value of the cylindrical coil may be narrowed.

(46) In the followings, results confirmed with different load torques T under identical equipments and identical control conditions are described. Each of the results is shown in FIGS. 13 to 17.

(47) FIG. 13 is a result of a driving test of the coreless motor 10 in which the load torque T.sub.1 is set to T.sub.1=0.33 Nm with the variable load 33 of the electric generator 32. As apparent from FIG. 13(a), during an operation test of the coreless motor 10, the coreless motor 10 is operated such that the cylindrical coil 100 is maintained within a certain temperature range by an on/off pulse operation of the refrigerant liquid supply pump 22, with the torque T.sub.1 maintained at 0.33 Nm. More specifically, the temperature t of the cylindrical coil 100 exceeds the cooling start temperature (t.sub.L1=123° C.) in around 100 seconds after start-up of the coreless motor 10. At this moment, the refrigerant liquid (pure water) 80 is directly supplied to the cylindrical coil 100 through the slits which respectively penetrates into the inner yoke. Then, when the cylindrical coil 100 is cooled by latent heat of vaporization and falls below the cooling stop temperature (t.sub.L2=122° C.), the supply of the refrigerant liquid (pure water) 80 is stopped, With repetition of such pulse operation, the temperature t of the cylindrical coil shifts in a range between 111° C. and 125° C. which is the certain temperature range. FIG. 13(a) is what has excerpted a period from when the coreless motor 10 is started up to when 720 seconds (12 minutes) has passed in a continuous operation test, and we have confirmed that the temperature shift for a period from 720 seconds (12 minutes) onward is almost similar.

(48) FIG. 13(b) is a diagram which has enlarged a temperature waveform of the cylindrical coil 100 of 3 minutes from when 180 seconds (3 minutes) has passed from the start-up up to when 360 seconds (6 minutes) has passed from the start-up, which is after cooling has started. A condition where rapid cooling is caused can be easily determined from the figure. The first read-in temperature t.sub.L1 is 123° C., and when the cooling is started by supplying the refrigerant liquid 80 at a temperature t exceeding such temperature, the temperature increase due to overshoot is around within 2° C., and become reversed immediately thereafter. The second read-in temperature t.sub.L2 after reverse is 122° C., and even when the supply of the refrigerant 80 is stopped at a temperature t which is below such temperature, the temperature after decrease further decreases by around 11° C. to 7° C. due to overshoot. Specifically, the maximum temperature t.sub.c1=125° C., the minimum temperature t.sub.c2=111° C., and .sub.Δt=14° C., of the cylindrical coil under control, with the load torque set to T.sub.1=0.33 Nm. Therefore, we have confirmed that, a normal continuous operation is possible by controlling such that the temperature difference .sub.Δt between the maximum temperature t.sub.c1 and the minimum temperature t.sub.c2 of the cylindrical coil 100 under control comes narrow, under a condition where the temperature of the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M=130° C. and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes.

(49) FIG. 14 is a result of a driving test of the coreless motor 10 in which the load torque T.sub.2 is set to T.sub.2=0.36 Nm with the variable load 33 of the electric generator 32. As apparent from FIG. 14(a), during the operation test of the coreless motor 10, the coreless motor 10 is operated such that the cylindrical coil 100 is maintained within a certain temperature range by the on/off pulse operation of the refrigerant liquid supply pump 22, with the torque T.sub.2 maintained at 0.36 Nm. The temperature t of the cylindrical coil 100 exceeds the cooling start temperature (t.sub.L1=123° C.) in around 90 seconds after start-up of the coreless motor 10. At this moment, the refrigerant liquid (pure water) 80 is directly supplied to the cylindrical coil 100. Then, when the cylindrical coil 100 is cooled by latent heat of vaporization and falls below the cooling stop temperature (t.sub.L2=122° C.), the supply of the refrigerant liquid (pure water) 80 is stopped. With repetition of such pulse operation, the temperature t of the cylindrical coil shifts in a range between 113° C. and 128° C. which is the certain temperature range. FIG. 14(a) is what has excerpted a period from when the coreless motor 10 is started up to when 720 seconds (12 minutes) has passed in a continuous operation test, and we have confirmed that the temperature shift for a period from 720 seconds (12 minutes) onward is almost similar.

(50) During the operation test of the coreless motor 10, a total pump operation time of 10 minutes from when the refrigerant liquid supply has started for case of the torque T.sub.1 is 56 seconds, on the other hand, it is 85.5 seconds for the case of the torque T.sub.2. The supply amount of the refrigerant liquid during such period is 3.62 ml for the case of the torque T.sub.1, on the other hand, it is 5.53 ml for the case of the torque T.sub.2, and it is 1.5 times more compared with the case of the torque T.sub.1 (FIGS. 11 and 12).

(51) FIG. 14(b) is a diagram which has enlarged a temperature waveform of the cylindrical coil 100 of 3 minutes from when 180 seconds (3 minutes) has passed from the start-up up to when 360 seconds (6 minutes) has passed from the start-up, which is after cooling has started. A condition where rapid cooling is caused can be easily deter fined from the figure. The first read-in temperature is t.sub.L1 is 123° C., and when the cooling is started by supplying the refrigerant liquid 80 at a temperature t exceeding such temperature, the temperature increase due to overshoot is around 5° C., and then reversed. The second read-in temperature t.sub.L2 after reverse is 122° C., and even when the supply of the refrigerant 80 is stopped at a temperature t which is below such temperature, the temperature after decrease further decreases by around 9° C. to 5° C. due to overshoot. Specifically, the maximum temperature t.sub.c1=128° C., the minimum temperature t.sub.c2=113° C., and .sub.Δt=15° C., of the cylindrical coil under control, with the load torque set to T.sub.2=0.36 Nm. A pulse interval becomes shorter compared with the case for the torque T.sub.1=0.33 Nm. We have confirmed that, a normal continuous operation is possible also for this case by controlling such that the temperature difference .sub.Δt between the maximum temperature t.sub.c1 and the minimum temperature t.sub.c2 of the cylindrical coil 100 under control comes narrow, under a condition where the temperature of the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M=130° C. and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes.

(52) FIG. 15 is a result of a driving test of the coreless motor 10 in which the load torque T3 is set to T3=0.39 Nm with the variable load 33 of the electric generator 32. As apparent from FIG. 15(a), during the operation test of the coreless motor 10, the coreless motor 10 is operated such that the cylindrical coil 100 is maintained within a certain temperature range by the on/off pulse operation of the refrigerant liquid supply pump 22, with the torque T.sub.3 maintained at 0.39 Nm. The temperature t of the cylindrical coil 100 exceeds the cooling start temperature (tL1=123° C.) in around 50 seconds after start-up of the coreless motor 10. At this moment, the refrigerant liquid (pure water) 80 is directly supplied to the cylindrical coil 100. Then, when the cylindrical coil 100 is cooled by latent heat of vaporization and falls below the cooling stop temperature (tL2=122° C.), the supply of the refrigerant liquid (pure water) 80 is stopped. With repetition of such pulse operation, the temperature t of the cylindrical coil shifts in a range between 109° C. and 128° C. which is the certain temperature range. FIG. 15(a) is what has excerpted a period from when the coreless motor 10 is started up to when 720 seconds (12 minutes) has passed in a continuous operation test, and we have confirmed that the temperature shift for a period from 720 seconds (12 minutes) onward is almost similar.

(53) During the operation test of the coreless motor 10, a total pump operation time of 10 minutes from when the refrigerant liquid supply has started for the case of the torque T.sub.1 is 56 seconds, on be other hand, it is 128 seconds for the case of the torque T.sub.3. The supply amount of the refrigerant liquid during such period is 3.62 ml for the case of the torque T.sub.1, on the other hand, it is 8.28 ml for the case of the torque T.sub.3, and it is 2.3 times more compared with the case of the torque T.sub.1 (FIGS. 11 and 12).

(54) FIG. 15(b) is a diagram which has enlarged a temperature waveform of the cylindrical coil 100 of 3 minutes from when 180 seconds (3 minutes) has passed from the start-up up to when 360 seconds (6 minutes) has passed from the start-up, which is after cooling has started. A condition where rapid cooling is caused can be easily determined from the figure. The first read-in temperature t.sub.L1 is 123° C., and when the cooling is started by supplying the refrigerant liquid 80 at a temperature t exceeding such temperature, the temperature increase due to overshoot is around 5° C., and then reversed. The second read-in temperature t.sub.L2 after reverse is 122° C., and even when the supply of the refrigerant 80 is stopped at a temperature t which is below such temperature, the temperature after decrease further decreases by around 13° C. to 5° C. due to overshoot. Specifically, the maximum temperature t.sub.c1=128° C., the minimum temperature t.sub.c2=109° C., and .sub.Δt=19° C., of the cylindrical coil under control, with the load torque set to T.sub.3=0.39 Nm. A pulse interval becomes further shorter compared with the case for the torque T.sub.2=0.36 Nm. We have confirmed that, a normal continuous operation is possible also for this case by controlling such that the temperature difference .sub.Δt between the maximum temperature t.sub.c1 and the minimum temperature t.sub.c2 of the cylindrical coil 100 under control comes narrow, under a condition where the temperature of the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M=130° C. and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes.

(55) FIG. 16 is a result of a driving test of the coreless motor 10 in which the load torque T.sub.4 is set to T.sub.4=0.42 Nm with the variable load 33 of the electric generator 32. As apparent from FIG. 16(a), during the operation test of the coreless motor 10, the coreless motor 10 is operated such that the cylindrical coil 100 is maintained within a certain temperature range by the on/off pulse operation of the refrigerant liquid supply pump 22, with the torque T.sub.4 maintained at 0.42 Nm. The temperature t of the cylindrical coil 100 exceeds the cooling start temperature (t.sub.L1=123° C.) in around 40 seconds after start-up of the coreless motor 10. At this moment, the refrigerant liquid (pure water) 80 is directly supplied to the cylindrical coil 100. Then, when the cylindrical coil 100 is cooled by latent heat of vaporization and falls below the cooling stop temperature (t.sub.L2=122° C.), the supply of the refrigerant liquid (pure water) 80 is stopped. With repetition of such pulse operation, the temperature t of the cylindrical coil shifts in a range between 107° C. and 127° C. which is the certain temperature range. FIG. 16(a) is what has excerpted a period from when the coreless motor 10 is started up to when 720 seconds (12 minutes) has passed in a continuous operation test, and we have confirmed that the temperature shift for a period from 720 seconds (12 minutes) onward is almost similar.

(56) During the operation test of the coreless motor 10, a total pump operation time of 10 minutes from when the refrigerant liquid supply has started for the case of the torque T.sub.1 is 56 seconds, on the other hand, it is 176.5 seconds for the case of the torque T.sub.4. The supply amount of the refrigerant liquid during such period is 3.62 ml for the case of the torque T.sub.1, on the other hand, it is 11.41 ml for the case of the torque T.sub.4, and it is 3.2 times more compared with the case of the torque T.sub.1 (FIGS. 11 and 12).

(57) FIG. 16(b) is a diagram which has enlarged a temperature waveform of the cylindrical coil 100 of 3 minutes from when 180 seconds (3 minutes) has passed from the start-up up to when 360 seconds (6 minutes) has passed from the start-up, which is after cooling has started, A condition where rapid cooling is caused can be easily determined from the figure. The first read-in temperature t.sub.L1 is 123° C., and when the cooling is started by supplying the refrigerant liquid 80 at a temperature t exceeding such temperature, the temperature increase due to overshoot is around 4° C., and then reversed. The second read-in temperature t.sub.L2 after reverse is 122° C., and even when the supply of the refrigerant 80 is stopped at a temperature t which is below such temperature, the temperature after decrease further decreases by around 15° C. to 7° C. due to overshoot. Specifically, the maximum temperature t.sub.c1=127° C., the minimum temperature t.sub.c2=107° C. and .sub.Δt=20° C., of the cylindrical coil under control, with the load torque set to T.sub.4=0.42 Nm. A pulse interval becomes further shorter compared with the case for the torque T.sub.3=0.39 Nm. We have confirmed that, a normal continuous operation is possible also for this case by controlling such that the temperature difference .sub.Δt between the maximum temperature t.sub.c1 and the minimum temperature t.sub.c2 of the cylindrical coil 100 under control comes narrow, under a condition where the temperature of the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M=130° C. and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes.

(58) As apparent from FIGS. 13 to 16, we have confirmed that the continuous operation of the coreless motor 10 is possible by controlling the temperature of the cylindrical coil 100, with the load torque T.sub.1 to T.sub.4 (0.33 to 0.42 Nm) exceeding a rated torque T.sub.0=0.28 Nm being continuously applied to the cureless motor 10. From these test results, in any of these cases of T.sub.1 to T.sub.4, it is confirmed that a normal continuous operation of the cureless motor 10 is possible by controlling the temperature of the cylindrical coil 100, in which the cylindrical coil 100 vaporizes the supplied refrigerant liquid (pure water) 80, and with the latent heat of vaporization, the temperature difference .sub.Δt between the maximum temperature t.sub.c1 and the minimum temperature t.sub.c2 of the cylindrical coil 100 comes narrow, under a condition where the temperature of the cylindrical coil 100 does not exceed the allowable maximum temperature t.sub.M and does not fall below the minimum temperature t.sub.N where the refrigerant liquid (pure water) vaporizes.

(59) It is verified that the coreless motors 10 in each of the four cases under the overload condition is capable of being operated continuously with the cylindrical coil 100 being in a completely controlled state and within an appropriate temperature range such as, the maximum temperature t.sub.c1=125° C., the minimum temperature t.sub.c2=111° C., .sub.Δt=14° C. (T.sub.1), the maximum temperature t.sub.c1=128° C., the minimum temperature t.sub.c2=113° C., .sub.Δt=15° C. (T.sub.2), the maximum temperature t.sub.c1=128° C., the minimum temperature t.sub.c2=109° C., .sub.Δt=19° C. (T.sub.3), the maximum temperature t.sub.c1=127° C., the minimum temperature t.sub.c2=107° C., .sub.Δt=20° C. (T.sub.4), by adjusting the supply amount of the refrigerant liquid (pure water) 80 to the cylindrical coil 100.

(60) Further driving test is performed to reinforce the verifications by the driving tests of the coreless motor 10 in each of the four cases under the overload condition. It is a test where the load torque is set to T.sub.1=0.33 Nm, which is set by the variable load 33 of the electric generator 32, to drive the cureless motor 10 from start-up up to when 300 seconds (5 minutes) passes, then the load torque is set to T.sub.4=0.42 Nm for the next 300 seconds to 600 seconds (another 5 minutes) to drive the cureless motor 10, and the load torque is set to T.sub.1=0.33 Nm again for the next 600 seconds to 720 seconds (further 2 minutes) to drive the cureless motor 10.

(61) FIG. 17 is a test result of the coreless motor 10 being continuously driven for 5 minutes with the torque 5 minutes with the torque T.sub.4, and 2 minutes with the torque T.sub.1 again. As apparent from FIG. 17(a), during the operation test of the cureless motor 10, the temperature t of the cylindrical coil shifts in a range between 109° C. and 126° C., which is the certain temperature range, even under a condition where the load torque is set to T.sub.1=0.33 Nm to drive the coreless motor 10 from start-up up to when 300 minutes (5 minutes) passes, then the load torque is set to T.sub.4=0.42 Nm for next 300 seconds to 600 seconds (another 5 minutes), with repetition of the on/of pulse operation of the refrigerant liquid supply pump 22. FIG. 17(a) is what has excerpted a period from when the cureless motor 10 is started up to when 720 seconds (12 minutes) has passed in a continuous operation test, and we have confirmed that the temperature shift for a period from 720 seconds (12 minutes) onward is almost similar.

(62) The condition for the refrigerant liquid supply pump 22 to operate is when the cooling start (the first read-in) temperature t.sub.L1=123° C. is exceeded as in the above cases. At this moment, the refrigerant liquid (pure water) 80 is directly supplied to the cylindrical coil. Then, when the cylindrical coil 100 is cooled by latent heat of vaporization and the temperature falls below the cooling stop (the second read-in) temperature t.sub.L2=122° C., the supply of the refrigerant liquid (pure water) 80 is stopped.

(63) FIG. 17(b) is a detail of a part where the load torque is instantaneously changed from T.sub.1=0.33 Nm to T.sub.4=0.42 Nm. Specifically, it is a diagram which has enlarged a temperature waveform of the cylindrical coil 100 of 4 minutes from when 180 seconds (3 minutes) has passed from the start-up up to when 420 seconds (7 minutes) has passed from the start-up. More specifically, since the load torque T.sub.1 is 0.33 Nm from 180 seconds (3 minutes) to 300 seconds (5 minutes), rapid cooling and slow temperature increase can be easily determined from the figure. The first read-in temperature t.sub.L1 is 123° C., and when the refrigerant liquid 80 is supplied to start cooling at a temperature t exceeding such temperature, the temperature increase is within around 1° C. and then reversed. The second read-in temperature t.sub.L2 after reverse is 122° C., and even when the supply of the refrigerant 80 is stopped at a temperature t below such temperature, the temperature after decrease further decreases by around 11° C. to 7° C. due to overshoot. Specifically, the maximum temperature t.sub.c1=124° C., the minimum temperature t.sub.c2=111° C., and .sub.γt=13° C. of the cylindrical coil of 2 minutes from when 180 seconds (3 minutes) has passed from the start-up up to when 300 seconds (5 minutes) has passed from the start-up, with the load torque set to T.sub.1=0.33 Nm, which almost corresponds with the result of FIG. 13, where the maximum temperature t.sub.c1=125° C., the minimum temperature t.sub.c2=111° C. and .sub.Δt=14° C.

(64) Since the load torque T.sub.4 is 0.42 Nm from 300 seconds (5 minutes) to 420 seconds (7 minutes), rapid cooling and rapid increase of temperature can be easily determined from the figure. The first read-in temperature t.sub.L1 is 123° C., and when the refrigerant liquid 80 is supplied to start cooling at a temperature t exceeding such temperature, the temperature, increase is within around 4° C. and then reversed. The second read-in temperature t.sub.L2 after reverse is 122° C., and even when the supply of the refrigerant 80 is stopped at a temperature t below such temperature, the temperature after decrease further decreases by around 13° C. to 10° C. due to overshoot. Specifically, the maximum temperature t.sub.c1=125° C., the minimum temperature t.sub.c2=109° C., and .sub.Δt=17° C. of the cylindrical coil of 2 minutes from 300 seconds (5 minutes) to 420 seconds (7 minutes), with the load torque set to T.sub.4=0.42 Nm, which almost corresponds with the result of FIG. 16, where the maximum temperature t.sub.c1=127° C., the minimum temperature t.sub.c2=108° C., and .sub.Δt=19° C. It is thereby confirmed that, even under a load change during operation of the coreless motor 10 where the torque 0.42 Nm is the maximum, it is capable of being appropriately controlled for continuous operation.

(65) FIG. 18 is an experiment result when the cooling start temperature t.sub.L1 and the cooling stop temperature t.sub.L2 of the cylindrical coil 100 are changed, with the condition of the torques being identical as shown in FIG. 17, It is a test result of the coreless motor 10 in which, the coreless motor 10 is started, the cooling start temperature is set when the temperature of the cylindrical coil 100 is t.sub.L1=110° C., the cooling stop temperature is set when the temperature of the cylindrical coil 100 is t.sub.L2=90° C., and continuously driven for 5 minutes with the torque T.sub.1, 5 minutes with the torque T.sub.4, and 2 minutes with the torque T.sub.1 again. In a case where set values of the cooling start temperature t.sub.L1 and the cooling stop temperature t.sub.L2 are changed, it is confirmed that the driving system 1 can also operate normally.

(66) The driving tests in the above are performed using pure water of vaporization heat 2257 kJ/kg described in a table of FIG. 19 as the refrigerant liquid. FIG. 19 is a list for melting temperature ° C., boiling temperature ° C., vaporization heat kJ/kg of the refrigerant liquid including pure water 80. Here, a driving test is performed respectively for a case with and without the refrigerant, where a fluorinated liquid, with melting temperature −123° C., boiling temperature 34° C. and vaporization heat 142 kJ/kg, is used as the refrigerant liquid 80, and the coreless motor 10, with the load torque set to T=0.317 Nm, is used.

(67) FIG. 20 represents a respective shift of temperature t of the cylindrical coil 100 in a driving test which uses a fluorinated refrigerant liquid as the refrigerant 80, for a case where the refrigerant liquid supply pump 22 is driven with the refrigerant liquid 80 being supplied to the cylindrical coil 100 and a case without the supply thereof, and the operation condition of the refrigerant liquid supply pump 22 is set such that the cooling start temperature t.sub.L1=54° C. (the first read-in) and the cooling stop temperature t.sub.L2=52° C. (the second read-in). By this driving test, it is confirmed that, in the operated coreless motor 10, in a case where the fluorinated refrigerant liquid 80 is supplied, the temperature of cylindrical coil 100 may be shifted between 50° C. to 60° C., on the other hand, in a case where the fluorinated refrigerant liquid 80 is not supplied, the temperature of the cylindrical coil 100 exceeds 130° C. in about 10 minutes.

(68) The result of the driving test revealed that the cooling operation to the cylindrical coil 100 by latent heat of vaporization, in which the fluorinated refrigerant liquid 80 is supplied to the cylindrical coil 100 and be vaporized with cylindrical coil 100, is also appropriately controlled by the controlling device 20. It is also verified that, in the coreless motor 10 which uses the refrigerant liquid 80 other than pure water, if the cooling operation to the cylindrical coil 100 can be appropriately controlled, the continuous operation of the coreless motor 10 is possible, and it is confirmed that change of the refrigerant allows change of temperature control range of the coil.

(69) As apparent from the present driving test using the coreless motor 10 of FIG. 8, the present invention is a coreless rotating electrical machine for being operated under a load exceeding a rated load, a driving method thereof, and a driving system including thereof, which at least has the following configurations.

(70) The coreless rotating electrical machine typically has a rotor equipped with a plurality of magnets on an inner surface of a cylindrical mount, or a rotor in which a plurality of magnets are equipped with intervals with respect to each other in a circumferential direction on an outer surface of an inner yoke and/or an inner surface of an outer yoke of a cup-type mount to which the concentric inner yoke and the outer yoke are integrated, and provided with slits, each of which passing through the inner yoke, at positions of the inner yoke corresponding to each of the intervals, or either of them as a constituent requirement, and a stator, which is the other constituent requirement corresponding to the rotor, has an energizable coreless cylindrical coil and consists of a lid-type mount which fixes one of end faces of the cylindrical coil.

(71) As apparent from FIGS. 1, 2 and FIGS. 3 and 4, it further has a channel for supplying a refrigerant liquid to an air space formed by an inner side of the cylindrical coil fixed to the stator and a center part of the rotor and the stator, and has a configuration in which a controlling part or controlling device is activated when driven by a driving part or driving device to adjust a supply amount of the refrigerant to be directly fed to the inner surface of the cylindrical coil via the channel by properly detecting a temperature of the cylindrical coil which generates heat. This is what can be easily understood from FIGS. 5 and 6 which represent the driving system.

(72) It is easily estimated from the variable load 33 in the electric generator 32 of FIG. 7, which is a schematic diagram of a driving test, that the coreless rotating electric machine, the driving method thereof, and the driving system including thereof of the present invention are applicable to various load conditions exceeding a rating. Moreover, the size does not matter as long as a configuration thereof is the same as that of the coreless motor used for the driving test.

(73) The coreless rotating electric machine of FIG. 21 illustrated as a reference diagram is an example in which a configuration of supplying a refrigerant liquid is arranged in a second air space, instead of a first air space shown in FIGS. 3 and 4 which is the position where the refrigerant liquid is supplied. Also in this example, the refrigerant liquid fed to the second air space reaches the cylindrical coil, which generates heat, and vaporized, and the cooling of the cylindrical coil by the latent heat of vaporization is fully possible, and thus, we consider that it may be the coreless rotating electrical machine for being operated under the load exceeding the rating. However, the driving test of the coreless motor based on such configuration has not been performed.

(74) Although the present invention has been described for preferable embodiments, those skilled in the art may understand that various modifications may be made and elements may be replaced with equivalents without departing the scope of the present invention. Therefore, the present invention should not be limited to specific embodiments disclosed as the best mode of embodiments considered for implementing the present invention, and it Although the present invention has been described for preferable embodiments, those skilled in the art may understand that various modifications may be made and elements may be replaced with equivalents without departing the scope of the present invention. Therefore, the present invention should not be limited to specific embodiments disclosed as the best mode of embodiments considered for implementing the present invention, and the present invention encompasses all embodiments which belong to claims.

REFERENCE SIGNS LEST

(75) 1: Driving system 2: Stator 3: Rotor 4: Magnet 8: Channel for supplying refrigerant liquid 10: Coreless rotating electrical machine or coreless motor 20: Controlling part or controlling device 21: Coil temperature detecting sensor 22: Pump 23: Controller 24: Electromagnetic valve 25: Temperature and voltage recording device 26: Refrigerant liquid flow volume varying device 30: Driving part or driving device 31: Power meter 32: Electric generator 33: Variable load 34: Torque sensor 35: Torque meter 40: Air space or first air space including air gap 41: Gap between respective magnets 50: Second air space 60: Third air space 80: Refrigerant liquid or liquid phase 800: Gas phase of refrigerant liquid 81: Refrigerant liquid container 82: Circulating means or circulating and conveying pipe 100: Cylindrical coil 101: One of end faces of cylindrical coil 102: The other end face of cylindrical coil 110: Inner periphery side of cylindrical coil 120: Outer periphery side of cylindrical coil 200: Lid-type mount included in stator 2 240: Center part of lid-type mount 300: Cylindrical mount included in rotor 3 310: Inner surface of cylindrical mount 340: Center part of cylindrical mount 400: Cup-type mount included in rotor 3 401: One of end faces of cup-type mount 410: Bottom part of cup-type mount 420: Inner yoke included in cup-type mount 400 421: Inside of inner yoke 420 422: Outer surface of inner yoke 423: Slits which pass through inner yoke 420 430: Outer yoke included in cup-type mount 400 431: Inner surface of outer yoke 1000: Drive shaft